One‐pot Synthesis of Bis(dihydropyrimidinone‐4‐yl)benzene Using Boric Acid as a Catalyst

A simple effective synthesis of bis(dihydropyrimidinone-4-yl)benzene derivatives, using boric acid as catalyst, from isophthalic aldehyde or terephthalic aldehyde, 1,3-dicarbonyl compounds and urea or thiourea in glacial acetic acid was described. As the expansion of the classical Biginelli reaction, this method has the advantage of excellent yields 83%–94% and short reaction time 0.5–1.5 h.